Q: Excluding a range of memory in 2.2.5

Q: Excluding a range of memory in 2.2.5

Post by The Good/John Scholv » Wed, 11 Mar 1998 04:00:00



OK, I've been trying to install 2.2.5 on a Compaq Contura 4/25 laptop with
20MB of RAM, and I think I've found the problem. When the machine had 8MB
installed, everything was fine, but when I installed the upgrade to 20MB,
the kernel just crashes. At first I tought I had bad RAM, but a replacement
exhibited the same behavior and passed Compaq's diagnostic.

After a lengthy binary search process on the right value for option MAXMEM,
I've found that the largest value I can use is MAXMEM=(15*1024+768). There's
something evil going on in that 256K just beneath the 16MB address point,
and whenever I try to use it, the system freezes. I suspect Compaq is
remapping the ROM into that space, but I can only say "suspect" since
Compaq's technical support is brain dead and useless and cannot confirm or
deny my hypothesis.

Sadly, there is no way to turn that remapping off in the BIOS setup.

So, assuming that is the problem, is there a way to direct the 2.2.5 kernel
to skip that 256K chunk and still access the RAM above the 16MB point? It
bugs me that I have 4MB sitting up there that I can't get to. I know it
isn't FreeBSD's fault...I'm just hoping for a workaround.

Any help, as always, will be greatly appreciated!

Thanks,

John

--

      OUR WEB SITE IS UP!  Check out http://www.enteract.com/~good

 
 
 

Q: Excluding a range of memory in 2.2.5

Post by Mike » Wed, 11 Mar 1998 04:00:00



> OK, I've been trying to install 2.2.5 on a Compaq Contura 4/25 laptop with
> 20MB of RAM, and I think I've found the problem. When the machine had 8MB
> installed, everything was fine, but when I installed the upgrade to 20MB,
> the kernel just crashes. At first I tought I had bad RAM, but a replacement
> exhibited the same behavior and passed Compaq's diagnostic.

> After a lengthy binary search process on the right value for option MAXMEM,
> I've found that the largest value I can use is MAXMEM=(15*1024+768). There's
> something evil going on in that 256K just beneath the 16MB address point,
> and whenever I try to use it, the system freezes. I suspect Compaq is
> remapping the ROM into that space, but I can only say "suspect" since
> Compaq's technical support is brain dead and useless and cannot confirm or
> deny my hypothesis.

> Sadly, there is no way to turn that remapping off in the BIOS setup.

> So, assuming that is the problem, is there a way to direct the 2.2.5 kernel
> to skip that 256K chunk and still access the RAM above the 16MB point? It
> bugs me that I have 4MB sitting up there that I can't get to. I know it
> isn't FreeBSD's fault...I'm just hoping for a workaround.

> Any help, as always, will be greatly appreciated!

> Thanks,

> John

> --

>       OUR WEB SITE IS UP!  Check out http://www.enteract.com/~good

Do you have the RAM in your motherboard the right way?  When I upgraded
the memory in my computer from 8 Megs to 40 Megs, cc/gcc would always
die when doing a make world.  Then, I got out my computer's manual and
saw what I was doing wrong.

Correct:
|---------------------------------------|
|       Bank 0       |      Bank 1      |
|---------------------------------------|
| SIMM 1 |  SIMM 2   | SIMM 3 | SIMM 4  |
|---------------------------------------|
|  16 MB |  Empty    | 16 MB  | Empty   |
|---------------------------------------|

The way I had it:
|---------------------------------------|
|       Bank 0       |      Bank 1      |
|---------------------------------------|
| SIMM 1 |  SIMM 2   | SIMM 3 | SIMM 4  |
|---------------------------------------|
|  16 MB |  16 MB    |  Empty |  8 MB   |
|---------------------------------------|

 
 
 

1. memory range - IO range

sorry cos its not a unix specific question. i noticed that some
devices like the NIC and graphics adapter have a "memory"range and IO
range ( i actually saw it in windows). does memory range mean that
these devices have direct access ( not DMA/bus mastering) to the
system memory? or does is pertain to memory that is present in the
device which is mapped ? if so what does IO range mean? does unix
handle it the same way? i posted in comp.hardware and a winx group..
but i cudn't get satisfactory answers.

2. Newbie:Linux on this config.

3. How to exclude single ip-address form ip range?

4. comp.unix.sco Administrative FAQ

5. How to exclude numbers from IP-range

6. SSLeay-0.9.0b RSA question

7. Memory & Disk Qs

8. Microsoft May Get Slammed In Korea

9. excluding with /etc/exclude.rootvg

10. How do you do exclude memory from the kernel like "emm386 X=CC00-CFFF"

11. Monitor Sync range Versus Scan range

12. Exclude memory area?

13. Excluding memory